Numerous lightweight constructions, such as porches, greenhouses, penthouses, sun porches, skylights or the like, made from an assembly of metal profiles, in light alloys such as aluminum, are well known. However, such constructions, generally because they are too light, cannot support traditional roofs. There have also therefore been developed frameworks particularly of wood so as to provide elements of a sufficient cross section to ensure the support of the load. However, such structures have the drawback of using, for their interconnection, members such as pegs, tenons, mortises, joints, frames or butt joints which require on the one hand preliminary preparation in the shop with supplemental adjustment of the elements in place, and on the other hand a mounting and adaptation of the members which requires the skill of a carpenter and the know-how of this latter. Because of this, industrialization of such a type of framework is not foreseeable.
To overcome this drawback, various frameworks have already been proposed. Thus, the patent FR-A-2.624.153 describes a support structure for added constructions constituted by elements in the form of hollow beams of wood generally formed of plywood, each beam comprising internally a central hollowed portion and on its external surfaces at least one longitudinal groove adapted to receive the heel of a connecting member interconnecting one element to another so as to form a predetermined angle.
Such a type of structure provides only a partial solution to the problem because the fact of working with connecting members which directly penetrate the wood beam involves problems of rigidity as well as aesthetic problems.
Another structure in the form of hollow beams of plywood and comprising a core of internal stiffening material is described in the patent FR-A-2.667.011. In this patent, the connection means of two beams to each other are constituted by right angle braces fixed within the stiffening core of said beams. Because of this, the possibilities for the construction of a framework with such connecting members are severely limited.